1. Field of the Invention
The present invention relates to a headrest which is provided on the top of a seat back of a rear seat or an auxiliary seat next to a driver's seat associated with an automotive seat, and particularly relates to a movable headrest which is displaceable from a head support use position to a non-use position, to thereby permit a driver to attain a clear backward view field through the rear window of the automobile.
2. Description of Prior Art
Most ordinary headrests are located at the top of a front seat or rear seat and supported there by means what are generally called a stay for supporting the headrest, which generally forms a pair of stays.
The main purpose of the headrest is to ensure safety protection for the head of an occupant on the seat. But, the presence of such a headrest on the rear seat presents an obstacle against the backward view field of a driver on the front seat and prevents the driver from easily or safely steering the automobile to move backward. That is, when the driver turns his or her eyes backward to see the rear side of the automobile, the headrest on the rear seat becomes a hindrance against the backward view field of the driver and thus narrows that view field. Due to that reason, the driver feels it hard to safely steer the automobile backward.
Further, in driving the car, the forward view field needs also to be attained clearly for the driver, and in the case where an auxiliary seat is provided next to the driver's seat, the headrest on such auxiliary seat becomes now an obstacle against the driver's forward view field.
To solve the above-stated drawbacks, there has been proposed an improved headrest, as is known from the Japanese Laid-Open Utility Model Publication Nos. 62-7248 and 62-75740, for example.
According to those prior art, a motor is built in the seat back and the drive shaft of the motor is integrally fixed to a pinion gear which is in mesh with a sector gear. The sector gear is integral with the headrest stay, and therefore, a drive force of the motor is transmitted to those pinion and sector gears, which causes fore-and-aft rotation of the stay and thus the headrest. This is best disclosed from the U.M. Pub. No. 62-7248, and the other Pub. No. 62-75740 teaches a gear mechanism for causing the fore-and-aft rotation of the headrest. Thus, with those two prior art, the headrests is displaced from the use position where it rest upon the top of the seat back to the non-use position where it is located at a downward level, disappearing from the top of the seat back, so that the driver can attain a wide or unobstructed forward and backward view field, in both the rear seat and auxiliary seat.
However, both prior art are of such a structure that a motor is arranged within the seat back such that it is disposed at the upper part as well as at the central part of the seat back, and as a consequence thereof, the inward deflection of the cushion member of the seat back, which occurs when an occupant leans thereon, brings a deflected area of the seat back to contact with the motor, resulting thus in a hard strange and unpleasing touch on the occupant part. What is worse, the location of the motor at the upper part of the seat back gives a greater weight at that particular part of the seatback, which creates a non-stable state of the seat back.